The invention relates generally to applying radio frequency identification (RFID) tags to items, and in particular, to applying RFID tags to medication containers so that the RFID tag is not obtrusive, does not obscure the text labeling of the container, and functions with the closure.
There are a number of ways of identifying and tracking articles including visually, optically (bar coding, for example), magnetically, RFID, weighing, and others. Where an automatic system for tracking is desired, RFID is a candidate since identification data may be obtained wirelessly. RFID tags have decreased in cost, which has made them even more attractive for such an application.
Radio-frequency identification (“RFID”) is the use of electromagnetic energy (“EM energy”) to stimulate a responsive device (known as an RFID “tag” or transponder) to identify itself and in some cases, provide additionally stored data. RFID tags typically include a semiconductor device commonly called the “chip” on which are formed a memory and operating circuitry, which is connected to an antenna. Typically, RFID tags act as transponders, providing information stored in the chip memory in response to a radio frequency (“RF”) interrogation signal received from a reader, also referred to as an interrogator. In the case of passive RFID devices, the energy of the interrogation signal also provides the necessary energy to operate the RFID device.
RFID tags may be incorporated into or attached to articles to be tracked. In some cases, the tag may be attached to the outside of an article with adhesive, tape, or other means and in other cases, the tag may be inserted within the article, such as being included in the packaging, located within the container of the article, or sewn into a garment. The RFID tags are manufactured with a unique identification number which is typically a simple serial number of a few bytes with a check digit attached. This identification number is incorporated into the tag during manufacture. The user cannot alter this serial/identification number and manufacturers guarantee that each serial number is used only once. This configuration represents the low cost end of the technology in that the RFID tag is read-only and it responds to an interrogation signal only with its identification number. Typically, the tag continuously responds with its identification number. Data transmission to the tag is not possible. These tags are very low cost and are produced in enormous quantities.
Such read-only RFID tags typically are permanently attached to an article to be tracked and, once attached, the serial number of the tag is associated with its host article in a computer data base. For example, a particular type of medicine may be contained in hundreds or thousands of small vials. Upon manufacture, or receipt of the vials at a health care institution, an RFID tag is attached to each vial. Each vial with its permanently attached RFID tag will be checked into the data base of the health care institution upon receipt. The RFID identification number may be associated in the data base with the type of medicine, size of the dose in the vial, and perhaps other information such as the expiration date of the medicine. Thereafter, when the RFID tag of a vial is interrogated and its identification number read, the data base of the health care institution can match that identification number with its stored data about the vial. The contents of the vial can then be determined as well as any other characteristics that have been stored in the data base. This system requires that the institution maintain a comprehensive data base regarding the articles in inventory rather than incorporating such data into an RFID tag.
An object of the tag is to associate it with an article throughout the article's life in a particular facility, such as a manufacturing facility, a transport vehicle, a health care facility, a pharmacy storage area, or other environment, so that the article may be located, identified, and tracked, as it is moved. For example, knowing where certain medical articles reside at all times in a health care facility can greatly facilitate locating needed medical supplies when emergencies arise. Similarly, tracking the articles through the facility can assist in generating more efficient dispensing and inventory control systems as well as improving work flow in a facility. Additionally, expiration dates can be monitored and those articles that are older and about to expire can be moved to the front of the line for immediate dispensing. This results in better inventory control and lowered costs.
RFID tags may be applied to containers or articles to be tracked by the manufacturer, the receiving party, or others. In some cases where a manufacturer applies the tags to the product, the manufacturer will also supply a respective data base file that links the identification number of each of the tags to the contents of each respective article. That manufacturer supplied data base can be distributed to the customer in the form of a file that may easily be imported into the customer's overall data base thereby saving the customer from the expense of creating the data base manually. It has been noted that where the customer must create the data base, a manual method is often used. The customer's employee reads the RFID device identification and once received at the employee's computer, then manually types the data on the container into the computer data base associating it with the RFID device's identification. Such manual entry of data can result in a higher incidence of errors.
Many RFID tags used today are passive in that they do not have a battery or other autonomous power supply and instead, must rely on the interrogating energy provided by an RFID reader to provide power to activate the tag. Passive RFID tags require an electromagnetic field of energy of a certain frequency range and certain minimum intensity in order to achieve activation of the tag and transmission of its stored data. Another choice is an active RFID tag; however, such tags require an accompanying battery to provide power to activate the tag, thus increasing the expense and the size of the tag and making them undesirable for use in a large number of applications.
Depending on the requirements of the RFID tag application, such as the physical size of the articles to be identified, their location, and the ability to reach them easily, tags may need to be read from a short distance or a long distance by an RFID reader. Such distances may vary from a few centimeters to ten or more meters. Additionally, in the U.S. and in other countries, the frequency range within which such tags are permitted to operate is limited. As an example, lower frequency bands, such as 125 KHz and 13.56 MHz, may be used for RFID tags in some applications. At this frequency range, the electromagnetic energy is less affected by liquids and other dielectric materials, but suffers from the limitation of a short interrogating distance. At higher frequency bands where RFID use is permitted, such as 915 MHz and 2.4 GHz, the RFID tags can be interrogated at longer distances, but they de-tune more rapidly as the material to which the tag is attached varies. It has also been found that at these higher frequencies, closely spaced RFID tags will de-tune each other as the spacing between tags is decreased.
The read range (i.e., the range of the interrogation and/or response signals) of RFID tags is limited. For example, some types of passive RFID tags have a maximum range of about twelve meters, which may be attained only in ideal free space conditions with favorable antenna orientation. In a real situation, the observed tag range is often six meters or less. In addition to the above, the detection range of the RFID systems is typically limited by signal strength to short ranges, frequently less than about thirty centimeters for 13.56 MHz systems. Therefore, portable reader units may need to be moved past a group of tagged items in order to detect all the tagged items, particularly where the tagged items are stored in a space significantly greater than the detection range of a stationary or fixed single reader antenna. Alternately, a large reader antenna with sufficient power and range to detect a larger number of tagged items may be used. However, such an antenna may be unwieldy and may increase the range of the radiated power beyond allowable limits. Furthermore, these reader antennae are often located in stores or other locations where space is at a premium and it is expensive and inconvenient to use such large reader antennae. In another possible solution, multiple small antennae may be used but such a configuration may be awkward to set up when space is at a premium and when wiring is preferred or required to be hidden.
In the case of medical supplies and devices, it is desirable to develop accurate tracking, inventory control systems, and dispensing systems so that RFID tagged devices and articles may be located quickly should the need arise, and may be identified for other purposes, such as expiration dates or recalls. Automated dispensing cabinets (“ADC”) and similar cabinets used in a health care facility exist where the contents of the drawers of the cabinet need to be tracked; i.e., inventoried periodically. A large number of medical items, devices, and articles are located closely together in the drawers. RFID tracking systems for medications do exist and have been found to be particularly helpful in automating medication inventorying and tracking in medical facilities. One such system is the Intelliguard System from MEPS Real-Time, Inc. of Carlsbad, Calif.
Glass vials ranging in size from 1 ml to 50 ml used in the pharmaceutical industry to store liquid and powder medication can present challenges to RFID tagging due to their small size, metal cap, and FDA required product labeling. Small glass vials are used extensively in the US pharmaceutical industry. These vials can be as small as 0.625 inches (15.875 mm) in diameter and 1.25 inches (31.75 mm) tall. Liquid medication is generally stored in these vials; however, medication in powder form can also be stored in the vials.
These small vials are used to store as little as 1 ml and up to more than 100 ml of liquid medication. The glass vial is capped by a combination of rubber and metal materials. The rubber component serves two purposes:                1. The rubber material presses against the glass of the vial to form a seal that prevents the liquid from escaping the vial; and        2. An exposed area of rubber in the top of the cap provides access to the medication via a sharpened cannula or needle of a syringe for example.The metal portion, or “crimp,” of the cap presses the rubber material against the glass vial to safely secure the cap onto the vial.        
Tracking a very small glass medication vial, such as a 1 ml vial, with a UHF RFID tag is a challenge. This is principally due to the fact that most RFID tags operating in the United States in the UHF 915 MHz Industrial, Scientific, and Medical bands (“ISM”) are too large in size for attachment to the small vials. The small near-field tags that are typically attached to the bottom of the smallest vial have a very short read distance and can be rendered non-functional when stacked on top of the metal cap of an adjacent vial.
The performance of current RFID tracking tags, placed on or near the medication vial metal cap, is greatly reduced due to detuning of the RFID tag antenna. The best current method for tracking small medication vials, using UHF RFID technology, requires the placement of a small round (0.3 inch or 7.62 mm diameter) “near-field” tag on the bottom of the vial, as mentioned above. (Note—the term “near field” is used to refer to a UHF RFID tag that has been optimized for harvesting the near-field magnetic energy transmitted from a UHF antenna. These “near-field” tags exhibit very short read distances (6 to 12 inches or 15.24 to 30.48 mm) but are less susceptible to detuning from liquids contained in the items being tracked). The “near-field” UHF tags perform best when positioned parallel to a UHF transmit antenna which has also been optimized for “near-field” transmission. This orientation limitation requires that all medication vials be standing straight up, with the tags parallel to the antenna, in order that they be accurately and repeatedly identified. If a medication vial is in a different orientation, chances of accurate detection are lessened. The current RFID tag employed for UHF tracking medication vials can only be easily identified in one orientation (parallel to the transmit antenna). The performance of current RFID tracking tags, placed on or near the medication vial metal cap, is greatly reduced.
Containers containing prescription medications are also subject to FDA required labeling. The FDA regulations (21 CFR § 610.60) for container labels include the need to place certain information on the label. In particular, the following items shall appear on the label affixed to each container of a product capable of bearing a full label:                (1) The proper name of the product;        (2) The name, address, and license number of manufacturer;        (3) The lot number or other lot identification;        (4) The expiration date;        (5) The recommended individual dose for multiple dose containers;        (6) The statement: “Rx only” for prescription biologicals; and        (7) A Medication Guide, if required.        
If the container is capable of bearing only a partial label, the container shall show as a minimum the name (expressed either as the proper or common name), the lot number or other lot identification and the name of the manufacturer; in addition, for multiple dose containers, the recommended individual dose. Containers bearing partial labels shall be placed in a package which bears all the items required for a package label.
Such “labels” may consist of a physical base material on which is formed a principal display panel (“PDP”), which is defined by the FDA as “the panel of a label that is most likely to be displayed, presented, shown, or examined by the end user.” In most cases there is a border on the label material surrounding the PDP that contains no information. The label may be attached to the medication container through various means, one of which is with adhesive. For the purposes of this application, when referring to a label the inventor intends to mean the PDP. In most cases, the base material does not completely surround the side of the container so that one end of the label meets the other end when it is mounted. Usually, there is space between the ends of the label when it is mounted to the vial or container. But in most cases, there is space between the ends of the PDP when the base material of the label is mounted to the container, as is shown in FIG. 1.
Referring now to FIG. 1 with more particularity, a typical label base material 35 is mounted to a medication container or vial 30. The PDP on this label base material is indicated by numeral 36. The ends 40 and 42 of the label base material do not meet when the label is applied to the container and there is space 44 between the ends of the base material. There is therefore also space between the ends 38 and 39 of the PDP since the PDP is part of and is smaller than the base material. In cases where the base material ends meet when the label is applied to a container, the ends of the PDP may still have space between them on the container. As will be discussed below, this space between the ends of the PDP is used to mount an RFID device permanently to the container to enable wireless identification of the container by RF energy. In particular, an RFID system is described.
The label PDP is shown in FIG. 1 having dashed lines on it which are meant to indicate visually readable information. This usually includes text, such as drug identification and concentration, and may also include other information. Information on the PDP may also include graphic or non-text information. In the case of FIG. 1, a bar code 48 is also included near the closed end of the container.
Turning now to FIG. 2, there is a typical glass container or vial 34 having an opening 46 at the top 50 directly opposite a closed end 52 (shown in FIG. 1), a rubber stopper 47, and a crimp closure 32 having an opening 33 formed therein so that the stopper is accessible to penetration by a cannula for extraction of the item in the container, or for adding to the item in the container. As is well known to those of skill in the art, the crimp closure is used to secure the stopper in place at the opening of the container to seal the container.
Turning now to FIG. 3, a prior art “flag tag” identification system 56 is shown. In this view, the medical item container 30 is small in size and in this case is a 1 ml vial. There is a metallic crimp closure 32 around a rubber stopper (not shown) with the crimp closure having an opening 33 at the top through which a cannula may be used to interact with the medical item within the vial. The “flag tag” 56 is actually an RFID device 57 mounted to a substrate 58 that is flexible. The substrate is then taped 59 to the vial 30. The width of the substrate and tape is approximately equal in this case to the barrel portion 64 of the vial, due to the small size of the vial. In most cases, clear tape is used to attach the RFID device to the vial so that the visual information on the label 65 can be read through the tape. The RFID device 57 includes in this case a circuitry element 66 containing a memory and processor and other components, and first 67 and second 68 antenna elements. The two antenna elements provide two poles for this RFID device. Other antenna arrangements are possible, as is discussed below in more detail.
“Flag tag” RFID systems are used typically because the particular vial size is too small for mounting the RFID device on it. The flag tag is manually taped to the vial over the labeling and the identification number of the RFID tag is read into a data base for the medical item within the vial to which the tag is attached. The flag tagged medical item container can then be put into the medication “stream” within a facility and can be tracked by means of its associated RFID device. However, disadvantages exist. Such flag tags can inadvertently be pulled off the vial because they are fairly large and extend outward from the vial in a flag style. Gripping them by the substrate may cause the flag tag to pull off of the vial. They can be difficult to handle because of the flexibility of the RFID substrate, which may interact with flag tags of other small vials interfering with the orderly stocking of the vials in a drawer or other storage unit. When put into drawers of a storage device, such as an ADC, the flag tag can be torn from the medication vial by catching of the door or frame hardware.
Hence, a need has been recognized in the art for a wireless identification system that is useful for small medical item containers where the identification system is a part of the container and provides accurate detection and identification of the container. A need has also been recognized for an identification system that can be mounted to a medical item container that does not mask visually readable information of the labeling of the container. A further need has been recognized for an identification system that is small in size yet provides an antenna surface area large enough for accurate identification. The invention fulfills these needs and others.